1. Field of the Invention
The present invention relates to an etching method and a plasma processing apparatus.
2. Description of the Related Art
In order to perform a preferable etching in a substrate plasma etching process, a method of controlling a temperature of a surface of a substrate by using a heater and a cooling mechanism provided in a pedestal for receiving the substrate, is suggested. For example, in an etching process described in Japanese Laid-Open Patent Application Publication No. 10-303185, a process temperature that causes a surface temperature of a substrate to be maintained during an etching, is lower than a plasma heating temperature at which the substrate reaches a state of thermal equilibrium by being heated by plasma. Hence, the surface temperature of the substrate rises due to heat input from the plasma. Hence, Japanese Laid-Open Patent Application Publication No. 10-303185 supposes cooling the substrate by a cooling mechanism to keep the surface temperature of the substrate at the predetermined process temperature.
However, in Japanese Laid-Open Patent Application Publication No. 10-303185, a temperature of a coolant is set at about 20 degrees C. when the plasma heating temperature is 300 degrees C. and the process temperature is 87 degrees C. The disclosure in Japanese Laid-Open Patent Application Publication No. 10-303185 relates to a substrate surface temperature control method in a plasma process under room temperature. Moreover, in Japanese Laid-Open Patent Application Publication No. 10-303185, the temperature of the substrate surface is controlled as described above during the etching to solve a problem of what is called a micro loading. The micro loading is a problem of etching rate differences (non-uniformity) depending on hole sizes when etching via holes, contact holes and the like.
However, because the plasma processes under room temperature and an extremely low temperature environment are different from each other in process characteristics and temperature range to be controlled, problems caused by the heat input from the plasma sometimes differ from each other, and approaches to solve the problems may differ from each other.